SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8bd1047a5316e59ff65283af10e79c0a2f43192a8e455518e3cef7675afe144' 
  AND token = 'JIv/1VLZoPIR5ghzAwGtukiX0VMRCiLT+KdqZGGqZ6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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