SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7be556230279b6475cbe54509f6d61a88fbe7235b13518164728def851f4fbba' 
  AND token = 'RXWBLMD4CMlmYkpmrNjTMftd16eRBsfER8ypYLNDhRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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