SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fc989f0a74b575fddcf6b7bd5508c42e14968bf6c89e5340016e826c7eb0e97' 
  AND token = '5j/FX+Mv5kzJPFiZgoYSta8xq2kUKq4l1mSSm1PU8LE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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