SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcb590dd7aadd89838078dab2236cc31bff0c97ede0f3467d1e7a55695b8da67' 
  AND token = 'U46KhpMkU1ioDDF86CsG4tRH2GbYwJhnyRe6TcFoQC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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