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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d6ef78351bae1c3782d93fba3bf3335329f70fa7d36b7d62b4f955cdaa58197' 
  AND token = 'bTV5EQYRxlH1sSptz46Hhw6uHJCeMcoRfMx+Z0WrmZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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