SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6722f5e8bdebdb30e3a6b1c0a54db5ce5c67f7a0f091c12c1aed992c39afbd63' 
  AND token = '9BYPWkD6B8kqHP5CjfymKjp+SUUDBUlQgvFOVRxH4Us=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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