SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84638991f9c5cb9a709690af9d3d9e7290995a63e6cc2cddd00280b3d430cd44' 
  AND token = 'yyE/3v2XIPqnUKLPJNitl0tjkeaiYrKBLgn1EFv6TrA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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