SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3b8127ecebb4b1c7fc84e05a0d7970e77145511de53beb650ecc62131a35eaa' 
  AND token = 'P6+5E8mc5+vQcoqDiPYxCTXPNGgaNoUICQUcc/iNDsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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