SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a9a8b7c2332194145ecce685308daedc8a56cd10ffad7995dbafc42ead3bdb5' 
  AND token = '/ysuOB/o835RnGKBmmDWUxqCbFwOQ868uVALDXzESXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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