SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3f993f6b4499e35e5ef2cb2d5f3fef7f3f5d1b69b12197b8a2a7716793fad58' 
  AND token = 'I/N4Ab2PdTPcdNniR9/LpaUwdRoYX6J4whlPIOsUR0o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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