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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1852a93c84ea91bc1f8ec2c8193dfe3ceb036d4cce2a73c9bc089d8e0ff8ca36' 
  AND token = 'A//orqAw0bdE94/PCgsfiVPlWD3BMyjQ0dDbiiWoDAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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