SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '806d12176998820a0127a46c6495815915e2a2678a5dc745d1f3c6d4023fdb38' 
  AND token = 'T/MUST+lxIAMQC2gShnILsTs54qsKLx7wWkkuBYNyZ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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