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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ecf23963e4ee9458f7f7f71e7dbd9fd8b06fd5376c38aeb8d07f4183d4ba279' 
  AND token = 'f2dSYLRjAaWrQN9QWFcDhR+inZh7EN09BzKCyJBJDPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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