SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e146481d41454b87726a6bf53c2972ad87d7d0ef6b86b56ecf21c1a2c0effda2' 
  AND token = 'g53n/5ZVXxcJaiUK66u+RIBi4Jnm7CtJ8vpmwYDrN68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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