SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'edf8266dc7b58e875bc73f70046f5d9b2813ca5a509d4147ba71604c6d0a899f' 
  AND token = '+AJQSRUCTrTt+2w/elm4/YmWGqSNsjSnKVHYvBsADrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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