SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7d8540435c807f53323327835ad7e69d4682568cc32fca7b0b591802f125c15' 
  AND token = 'EhqCL0gFhzpgPO6fGH7PgjtM3+Gv6tvb8w6hSFdnt+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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