SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37ec968fbfdd008e386eb4bdca973bbb414530ee965e826e3443f4e96d20ffa1' 
  AND token = 'HqY7PwW15rFHloiJZ9YhcEdYdSFwfA4Yjni5ZQktc6k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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