SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e41a74eb23451d46308386ebcacfee1c521212704ca86dd56a09369c4ccd885' 
  AND token = 'BRg4baj52MB6ORfHV0namByFqsaGutRbiwOhxyAvatc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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