SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f4ad438f2ef048a8bd5344d3d404c15ae731c53e3e8485401260b066d134ad6' 
  AND token = '/9gL/OxWxWiGqAKd660LP0oW1cGrbJhI7rlJPcsxoQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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