SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '524520870cf31251f91cfbd14fefed4e22c6e044525c40abce85120fe8433712' 
  AND token = 'OrbbCjlmN6SHsl/Rex4JIRpyST1YismtVmmVhTOeihg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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