SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd81292f0636054ef35d6fe2903469b94d14450e66944233aaaa73a71df229405' 
  AND token = 'Qp2qYm2H8OqsB5BxRGBGdRq+tDwtRsFBJCNYflKmw+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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