SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c027f097b20d667a62273ec81fe84292138d23f987c9961e9a2313a13d3b84b9' 
  AND token = 'acREQKcL3qSvAMXdB1cmX9tgpALOv8Vww3SfvkgkZMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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