SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2547fab85ad8175643004602b6a70a8e3cbbed37fb0da11cae730e10474b84e' 
  AND token = 'n2PBJeiYAoDHSZGakdCQ56AaKGLlTOlFpd6AAShTrd4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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