SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6c92b690e31257ee733151979ce3ffbfda4789194c18513e0f052e30dd4bc31' 
  AND token = 'qbjGwUVhUfN4fxFkfSytgFVLuzj6rB9fMrHVou9+KIE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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