SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5a45492f90241af4b3e559d439eaae4c3cfdf5f444886584007948922bd6752' 
  AND token = 'PraK8tyNZ1+VDw/vnFgvwJEQ3WeO5mbe+o67rnMCJBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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