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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4ffb0b802d55b625d8c5995d796cfa570499f02ca7f3b46248dbc6bf6ecb50c' 
  AND token = 'gRmtb4eAUcc+nU5iTuh7D/14uI905lQ2yIGTjJ1NnOI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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