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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b86f469d8954d02478aa0b500ddda66a7ce40d969b579ab512f8cb4e9a8d8b20' 
  AND token = '/djhzdRaDjEDOCyeHzhOvOy+8Mqyiu0IWeE+o+CYqos=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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