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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50defdc5cd10de3c388d4fe4da7f67ba386e0d28a66d5a19a9d5231ad02289db' 
  AND token = 'c7ZQMDMiuOtlNZWL6TS8bg5xfzX8AFTcl+vklZ+jb4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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