SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71f7f37e5f9e3ff9af2b29e0b645ced2306657f729781b3666441ace3a740c42' 
  AND token = 'gnhdKPqcgxgQY6SVm1602gcQR5Jz6xN/EKESEyhW+A8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}