SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f96e7d4aa01b2416d85922d1d6c1e21ea7e5fcf980a8b740acd0b307100713f2' 
  AND token = 'N4pU6zcGc6LNtS8wEVZ/mk1+lslqtSLn5Htkyt3v9Ms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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