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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7ef6149bb3187ac1da49f71d2c53d87d8002b014672331a4c1a1a00bad41ab3' 
  AND token = 'cGYJnf3O1ZSiKq6pbtlhwgFiM8GA4fFPsDbcgIXBa9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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