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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8ffb1e031b336886deb20e233641bb27c8d0f4ac8da6c8f1fde437c48dd03b77' 
  AND token = 'IA5yWirTo5k9jJFXWslp3/rFqUX2pilldtd0H3utLKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}