SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b70c4fe8f403df0b5e988f3c059add4f714c8030dcd157875208490b27da24f6' 
  AND token = 'AotUUfX6/CSK9n5FP587DugKCnzJA3E4FPczq1A7Pjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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