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SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c5542fe2b40157c61c50eeca4427e1838aada4b90b3f18f94e0c86f13f1decae' 
  AND token = 'LUG9+NxuALt0fdtC+qd6ge38motfN20PatEi+MI4zfY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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