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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa4b8ce4a920798731cd5cbe3d52aa5fe4021ac4dbf222bbb2d5203b1522b4b8' 
  AND token = '4G/iWUvbPx13nPAbMsoVaYpFOf1YrSBhTycdUjBiJMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}