SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e961afa8ded7502c96868a4be71af5bef564d8848a36bf2495937c099c751ec2' 
  AND token = 'siHMHxFd6RMvFysz1fSfrl2wrtMhFc9+tepkyxTe42E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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