SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f65b56f3b2169e2d77bcc3989a6fd69731427ea55751765918f2e8049eae4fc9' 
  AND token = 'HnTklKq+noOODWyO1lgL0fHYw5dkqd7hwQCLB1k6oT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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