SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5e842d49fa87847cd6a3a64bffb017028be699feedf73d9d545a161b33b2253' 
  AND token = 'tfSS1+yc58KddvBfvKY9LxXFR0a8vlnWC5764EqqhBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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