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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9b99cfed8893e5737bb7c0b0b66bdec187bf2e3dce145ab82fb3a46785b1e54' 
  AND token = 'r39fFF2oFxoxBXIWT1AJ80IoSB8nZB+A/OijxNuTAnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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