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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '550ceb1d1179f1d6f36dc87d3cb92cbe3c6f8a13d847a1e8e57b17b4582f2571' 
  AND token = 'etgEmfhKX4CqkkS1bcOcRDVEh8q3hsgxVe1VqVrRm+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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