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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c755c46e24f9968b1ccc45543842da2dc2c2c8ddd40566b50e51bdabed8fdb47' 
  AND token = 'z9pleGCPI2BClFR92TqAPs3h84W8jG1AWzj+1gjFfKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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