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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9f90f84a64599dc8cee288cfe4dbdc94922ce6ce0f412beb10d5674a9428b15' 
  AND token = 'h6lXwtCRhy2tLCWoRVb94exS+/5L8NzYCcB7WwGMONc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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