SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42ef18a22f5e4e7612a8c83e7be7c4b151100d319d67f6f163b62cae092187ba' 
  AND token = '9Fp8YFT4JzWm6V/QjC+QmWrf5kRBYFgKvHGJmUqBMKI=' 
  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"
    }
  }
}