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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd52200a1c75bc8fdad5e93bebc8ab3a299b3b561ed36ffd50e2cbefda0bf6bd6' 
  AND token = 'BdhlEpdkoVLMxnG4Mra+SDk3BFXwlQYnPHeKRxYWpOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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