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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a3631622c62da1587ff45e674d0831ca8755259ed3d941b30835155cc0ac8ae' 
  AND token = 'Ld3QQ3jQoGuSuKVA2+QBfSDAAEQO18jmpOifG2IspO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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