SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b6d1c9b2855308272c08ac0e0f22088ad97588f5444a02b405a11c53ce9c8a0' 
  AND token = 'vBYm+9D4xKSQwh6bWm1bSAxuzF2yX6jmB/1qsWKj/IY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}