SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c3ec42de5ca513a12d2a445c1db76648854cf0f4b3c2c92e9443153c0970614' 
  AND token = 'qegcmOtL+AZD3tMzgU8c5vdDJ44RBPyjIMiXxXb9XKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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