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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a9b7771463b32d22b661e3ca9ba58875747dbc01d30842f7ccb0dc6e8e27fad' 
  AND token = '+zLmGubsCiIljFEsqPUx3f2bjA8ijWN0NSrPPMh+m4M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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