SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bec89b41e4d3bd932990d93a1532af46ec46f14bc1b0c158e6037c3da7732359' 
  AND token = 'PCs6q4HL9cEvJrN5fPOGnXzb0e2vZqzpIpynMJrJ0Sw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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