SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5e5bf7ae5828177fb25b4e699770c1d0b321e317108c469d41b2939265c9599' 
  AND token = 'OHlW57bT2cMi3MAzE7i1cuJmrOAQeIYbTEMFHcWGNyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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