SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b91d3fe2b6948a954483845bf2816d73c24ec189d30454b9714af6637d920932' 
  AND token = 'P4gg/tFsjK0tn0i6sDzKFkK/w3c+bPbAOEOZzABRO08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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