SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2b6bc65ed3fd3f6e0f718dc847c2f141b5cc02a93b2c3001a405d7ba10d8201' 
  AND token = 'BsTQKEHMKapAPVS7lumGBmgASMbrkoT4dbIHi/jScPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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