SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a57e2e843576341dfabf7e0fa6bc4e95cdf10f1caec899e79802c05d0a911a60' 
  AND token = 'E1qeB/ae2RmdsDkBjWnJPwBzznLfsG0IjgRNHdI7v/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}