SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f422b72b8e5a371222f2b418409ecfb4f14c39ebaa492a9d17276db4079392b9' 
  AND token = 'mFXBD1I2i+VjOmRZQpeqHNHUFAKOvXGbZna4QOUZyvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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