SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cac926123ddf96744f56e993c95d53a37e4d183122f90900901711202cbe88f4' 
  AND token = 'fGuzyVbU8XXNbXNxPLhVqclRCf8AWC4rAJC/a1bAhqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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