SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b251d3046695cc65c4462d57e674d6e1101d586929153cbe770d04283616927b' 
  AND token = 'bHgyA4mvLmpRPni2su85v4pt1RJW+70KcZ3pPQCd0ws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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