SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9738bdd4b604ba1523f12fbe8fa0b5d195febb0b798af84706fd76691d8bf405' 
  AND token = 'I8thFl5sChxhPOa45dE2VGqBc6GOBGdAiBbEKCustOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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