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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfc7293adbd6e8286ad8b3aca602ee6ae78138f8fd3177100e4ed4dd763a103a' 
  AND token = 'de7IF/HB3hFl3mUDpjjZUxNe6b9mJ0yvRZsGdEe31Qs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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