SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d3867ee9c84c6e78847c5e20f1a59cd8f0e20726079e9bf72e59411acf2d1ba' 
  AND token = 'AGRTR+Aq5mXULm051uLzCgnpb5EoVo1yKuwjZ1G58mQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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