SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78408eabae1c96d9cd5d1faa3b08624c1639203163b33195c23efe7429c5adf4' 
  AND token = 'T3FJbLvGgjuxhXQ/OP5Aqxy5/7s9KwTOXYztcHdtJhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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